I'm not a big Microsoft fan, but to their credit, I don't recall any cases where they've tried to use patents to push people around. They, and other large companies have no choice but to file a patent every time they take a crap in order to fend off patent trolls.

Their deal with Novell is a good counter-example to your claim.

They went to Novell, and made a deal along the lines of ... if you promise not to sue our customers over patents, then we won't sue yours. That probably sounded OK to Novel.

As soon as the deal was signed, Microsoft then blurted "all you users of Linux (other than Novell's) have an 'undisclosed liability' to Microsoft - Ballmer". They then tried to pressure Red Hat into a similar deal ... already having signed one with Novell over the same codebase!

If Microsoft truly want to protect their customers from patent threats from Linux and FOSS, such that they feel the need to sign patent covenants ... then what would be wrong with Microsoft just joining in the Patent Commons and the OIN ... that way they would get exactly the same protetction from patents for their customers for free!